1. Field of the Invention
The present invention relates to a technology for an automatic guided vehicle and a method for drive control of the same.
2. Description of the Related Art
In a production line of a factory or a warehouse, an automatic guided vehicle (AGV) that is made automatically run on a target drive route and loads and unloads cargos by automatic control is introduced to save labor and improve the accuracy of carriage. As methods for guiding such an automatic guided vehicle on a target drive route, various methods have been developed and applied.
For example, in an electromagnetic induction method, an induction magnetic field transmitted from an electric cable buried under a floor is detected by a coil mounted on an automatic guided vehicle; the drive velocity control and the steering control of the automatic guided vehicle are performed; and a drive following a target drive route is performed. For another example, in an optical method, a reflected light from a reflecting tape stuck on a floor is detected by an optical sensor mounted on an automatic guided vehicle; the drive velocity control and the steering control of the automatic guided vehicle are performed; and a drive following a target drive route is performed (For example, refer to Patent document 1, namely JP H04-006966 B2).
Further, in a magnetic induction method, the magnetism of a permanent magnet buried in a floor or a magnetic tape stuck on a floor surface is detected by a magnetic detection sensor mounted on an automatic guided vehicle; the drive velocity control and the steering control of the automatic guided vehicle are performed; and a drive following a target drive route is performed (For example, refer to Patent Document 2, namely JP 2005-339582 A).
Further, in a gyro method, detection is performed by a gyro sensor mounted on an automatic guided vehicle, and a reference position marker for position correction buried under a floor is detected by a sensor mounted on the automatic guided vehicle; the drive velocity control and the steering control of the automatic guided vehicle are performed; and a drive following a target drive route is performed (For example, refer to Patent Document 3, namely JP 2001-350520 A).
As another example, there is a laser method in which a reflecting plate for reflecting a laser light projected from an automatic guided vehicle is fitted on a wall, post, equipment, or the like in the periphery of a drive route; a reflected light of the laser light projected from the automatic guided vehicle is detected by a detection sensor for a laser reflection light mounted on the automatic guided vehicle; a position is identified by a computation process, such as a triangulation method, based on the light receiving angle of the reflected light; the drive velocity control and the steering control of the automatic guided vehicle are performed; and a drive following a target drive route is performed.
In the technologies described in Patent Documents 1 to 3, a movement target is designated by an address that is at a certain position in a drive area where an automatic guided vehicle runs; the automatic guided vehicle is driven to the address; and thus drive control is performed.
On the other hand, Patent Document 4, namely JP 4375320 B2 discloses a mobile robot that autonomously moves on a route by performing matching between measurement data that is collected by a laser distance sensor and map data that is set in advance and computing the current position.
However, in any of the above-described methods, arrangement is made such that a target drive route is fixed, and the drive direction is determined, corresponding to a deviation amount of a sensor. Further, in these methods, in general, a safety sensor is mounted on an automatic guided vehicle independently from a drive sensor; an obstacle or a person is recognized in a in a fixed area; and, as a result, when there is a problem with driving the automatic guided vehicle, the automatic guided vehicle is decelerated or stopped.
In the technologies described in Patent Documents 1 to 3, an automatic guided vehicle runs, following a drive route arranged in terms of hardware, with an electric cable, a reflecting tape, or the like, and stops by detecting the address of a movement target, which only enables driving with a low degree of freedom.
In the technology described in Patent Document 4, because a route is in general managed with coordinates, a drive control by an address, which has been used on a drive route as hardware, cannot be applied. That is, the technologies described in Patent Documents 1 to 3 and the technology described in Patent Document 4 are not compatible with each other.
Accordingly, when it is attempted to drive an automatic guided vehicle by the technology disclosed by Patent Document 4 in a system that has used the technology disclosed by any of Patent Documents 1 to 3, it is necessary to modify the entire system, which makes it difficult to introduce a self-driving automatic guided vehicle as one described in Patent Document 4.
The present invention has been developed in the above-described background, and an object of the invention is to provide an automatic guided vehicle and a method for drive control that enable driving based on a coordinate system while using designation of a movement target position by an address.